I have done a lot of long-haul flights over the years and have learned from those times when my luggage went one way and me another, to always pack a change of clothes, extra underwear and a nightie in my hand luggage!
Check lists are vital, as is an itinerary for when you arrive. Nothing worse than wasting precious days because you haven't planned out your sightseeing activities etc.
Photo copies of all your documents placed in the bottom of your suitcase, plus tape extra contact details inside same suitcase
Be ruthless with what you pack. Take only what you really need. It's too easy to over pack, then you have the problem of excess weight with all the goodies you had to buy to bring back.
It's also well worth getting your main suitcase plastic wrapped at the airport if you are going to any destination where security may not be up to par. It's a pain to get off on arrival, but well worth the knowledge that no-one has been able to help themselves to your stuff.
Retiring and living frugally in money from downsizing after years of stress




is all I can say!!